U.S. patent application number 16/026220 was filed with the patent office on 2018-11-08 for stand-alone fusion implant secured by in-line fixation.
This patent application is currently assigned to DEPUY SYNTHES PRODUCTS, INC.. The applicant listed for this patent is DEPUY SYNTHES PRODUCTS, INC.. Invention is credited to Michael Mazzuca.
Application Number | 20180317990 16/026220 |
Document ID | / |
Family ID | 59385226 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180317990 |
Kind Code |
A1 |
Mazzuca; Michael |
November 8, 2018 |
Stand-Alone Fusion Implant Secured by In-Line Fixation
Abstract
Stand alone fusion cage assemblies that can be secured to the
adjacent vertebral bodies via an in-line approach that is
substantially perpendicular to the anterior wall of the stand alone
cage (or substantially parallel to the cage insertion
direction).
Inventors: |
Mazzuca; Michael; (North
Easton, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DEPUY SYNTHES PRODUCTS, INC. |
Raynham |
MA |
US |
|
|
Assignee: |
DEPUY SYNTHES PRODUCTS,
INC.
Raynham
MA
|
Family ID: |
59385226 |
Appl. No.: |
16/026220 |
Filed: |
July 3, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15402926 |
Jan 10, 2017 |
10034699 |
|
|
16026220 |
|
|
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|
62278590 |
Jan 14, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/7082 20130101;
A61B 17/8615 20130101; A61B 17/8888 20130101; A61B 17/864 20130101;
A61B 17/8635 20130101; A61B 17/861 20130101; A61B 17/8883 20130101;
A61B 17/8605 20130101; A61B 17/862 20130101; A61B 17/8685 20130101;
A61B 17/8625 20130101 |
International
Class: |
A61B 17/86 20060101
A61B017/86; A61B 17/70 20060101 A61B017/70 |
Claims
1. A method of treating a spine, comprising the steps of: i)
inserting into a disc space an intervertebral fusion device having
an anterior wall, a posterior wall, and first and second side walls
connecting the anterior and posterior walls, an upper bearing
surface and a lower bearing surface, the anterior wall having a
height and an anterior surface, and a first threaded throughhole
extending into the anterior wall from the anterior surface, ii)
disposing into the first threaded throughole a fixation device
comprising a proximal head and an intermediate flexible bellows
having a helical threadform, wherein the helical threadform
threadably mates with the first threaded throughhole.
2. The assembly of claim 1 wherein the proximal head of the device
comprises an internal drive feature.
3. The assembly of claim 1 wherein the proximal head of the device
comprises an axial through hole.
4. The assembly of claim 1 wherein the axial through hole is
cylindrical.
5. The assembly of claim 1 wherein the axial through hole is
frustoconical.
6. The assembly of claim 1 wherein the proximal head of the device
is tapered and threaded.
7. The assembly of claim 1 wherein the proximal head of the device
has a peripheral groove.
8. The assembly of claim 1 further comprising c) a guidewire
extending through the fixation device.
9. The assembly of claim 8 further comprising d) a sleeve, wherein
the guide wire extends through the sleeve.
10. The assembly of claim 9 further comprising e) a centering guide
disposed in a hole in the intervertebral fusion device, wherein the
sleeve extends through the centering guide.
11. The assembly of claim 1 wherein the device further comprises a
distal tip.
12. The assembly of claim 11 wherein the distal tip has a tapered
thread.
13. The assembly of claim 11 wherein the head, bellow and tip are
independent elements joined by first and second joints.
Description
CONTINUING DATA
[0001] This patent application is a continuation of and claims
priority from co-pending US non provisional application U.S. Ser.
No. 15/402,926, filed Jan. 10, 2017, entitled "Stand-Alone Fusion
Implant Secured by In-Line Fixation" (Mazzuca et al.)
(DSP5218USNP), and from US provisional application U.S. Ser. No.
62/278,590, filed Jan. 14, 2016 entitled "Stand-Alone Fusion
Implant Secured by In-Line Fixation" (Mazzuca et al.)
(DSP5218USPSP), the specifications of which are incorporated by
reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] Stand-alone fusion cages have become popular in the field of
spinal fusion surgery because they can be used without the need for
posterior fixation. In general, at least two fixation devices (such
as screws or nails) are passed at an angle through the anterior
wall of the stand-alone cage and into the adjacent vertebral
bodies, thereby securing the stand-alone cage to the adjacent
vertebral bodies.
[0003] However, one challenge with these devices is that the need
to pass the fixation device at an angle to the cage requires that
the inserter also be disposed at an angle, thereby complicating the
surgery. In some fusion cases using a stand alone cage, the surgeon
must insert the fixation device into the cage at a sharp angle
through sometimes challenging approaches. This can be especially
difficult for the cervical spine, as the surgeon needs to either
deliver the screw down into the inferior vertebral body but may be
obstructed by the patient's chin, or deliver the screw up into the
superior vertebral body but may be obstructed by the patient's
sternum.
[0004] Therefore, there is a need to provide a stand alone fusion
assembly that can be secured to the adjacent vertebral bodies via
an in-line approach that is substantially perpendicular to the
anterior wall of the stand alone cage.
[0005] U.S. Pat. No. 6,551,322 (Lieberman) discloses using a double
helix as a fusion cage.
[0006] A number of investigators have attempted to solve the
above-stated problem by in-line inserting a helical element into
the in-situ cage. See for example, US 2002-0177898 (Crozet) U.S.
Pat. No. 7,056,341; U.S. Pat. No. 6,210,442 (Wing); WO 00/16711
(Meriwether), and WO2010/028056 (Synthes). However, each of these
solutions largely involves passing the helical element
substantially through the graft-containing region of the cage,
thereby reducing the space in the cage available for the critical
bone graft.
[0007] Although the helix of FIG. 23 of Crozet does not enter the
graft space, the height of Crozet's helix (a screw) would need to
be only slightly greater than the height of the cage in order to
avoid the hitting anterior lips of the adjacent vertebral bodies
during insertion. Also, screw backout could be an issue.
[0008] Moreover, in each of these prior art solutions, the
longitudinal axis of the helix is substantially parallel to the
upper and lower surfaces of the cage.
SUMMARY OF THE INVENTION
[0009] A number of solutions to the above stated problems have been
developed. Stand alone fusion cage assemblies that can be secured
to the adjacent vertebral bodies via an in-line approach that is
substantially perpendicular to the anterior wall of the stand alone
cage (or substantially parallel to the cage insertion
direction).
DESCRIPTION OF THE FIGURES
[0010] FIG. 1A is a perspective view of a hollow bellows having a
helical threadform.
[0011] FIG. 1B is an axial cross-sectional view of a hollow bellows
having a helical threadform.
[0012] FIG. 1C discloses a bellows screw comprising a proximal head
having a hollow center, an intermediate bellows section and a bored
distal tip.
[0013] FIG. 2A is a side view of the installation of a conventional
stand alone cage.
[0014] FIGS. 2B and 3 are side views of the installation of a stand
alone cage fixed with a hollow bellows screw.
[0015] FIG. 4 is a side view of an implanted stand alone cage fixed
with a hollow bellows screw.
[0016] FIG. 5 discloses a preferred screw.
[0017] FIGS. 6A-B disclose cross-sectional views of a first set of
preferred heads.
[0018] FIGS. 7A-B disclose a second set of preferred heads.
[0019] FIG. 8 discloses a preferred bellows.
[0020] FIGS. 9A-B disclose cross sections of preferred tips.
[0021] FIG. 10 discloses a preferred embodiment with mechanical
joints.
[0022] FIGS. 11A-B disclose a preferred method of inserting the
screw.
[0023] FIG. 12 is a perspective view of a conventional spherical
hex.
[0024] FIGS. 13-14 are perspective and cross-sectional views of a
screw-inserter assembly having a spherical hex joint.
[0025] FIGS. 15-16 are perspective and cross-sectional views of a
screw-inserter assembly having a projection slidably received in a
slot.
[0026] FIGS. 17A-B and 18 are side, perspective and cross-sectional
views of a screw-inserter assembly having a capped projection
slidably received in a slot.
DETAILED DESCRIPTION OF THE INVENTION
[0027] For the purposes of the present invention, a "helix"
includes structures that have less than a full period of a
helix.
[0028] Bellows Embodiment
[0029] In preferred embodiments, the helix is present in the form
of a helical bellows 1, as shown in FIG. 1A.
[0030] A traditional metal bellows is a metallic flexible
compressible hollow cylindrical structure; the walls are thin and
corrugated. The ridges and furrows of the walls facilitate the
flexibility of the structure, and as long as the material yield
strength is not exceeded the bellow will return to its original
form after deformation. Typically the corrugations run parallel to
each other and perpendicular to the axis of the cylinder. Metal
bellows can be manufactured through forming, welding, or
electroforming. Forming bellows involves rolling, deep drawing, or
hydroforming. Formed bellows typically have thick walls resulting
in reduced flexibility when compared to welded or electroforming.
Material choices for formed bellows are restricted to metals with
high ductility. Welded bellows are made by edge welding a stack of
formed rings. Weld location alternating between the inside and
outside edge creates the bellows. Wall thickness is thin and
flexibility is high. Electroformed metal bellows are produced by
electrodeposition, where a thin layer of metal is electrically
deposited on to an aluminum form called a mandrel. The mandrel is
precision machined and comprises the geometry of the finished form.
Once the desired thickness of material (typically nickel, copper,
gold, silver, or a combination of their alloys) is deposited on the
mandrel the aluminum is chemically removed leaving behind the
finished bellows.
[0031] By changing the corrugations from parallel to a helix, a
flexible thread form can be produced similar to a metal bellows.
The hollow center would allow it to slide over a rod-like
structure, and the flexibility would enable it to conform if the
rod was curved. A drive feature at one end delivers the means for
rotation, and the helical threads provide a method to advance the
flexible screw.
[0032] FIG. 1B shows a cross section of the helical bellows-type
flexible screw 3.
[0033] FIG. 1C discloses a bellows screw comprising a proximal head
5 having a hollow center 6, an intermediate bellows section 7 and a
bored distal tip 9.
[0034] The flexible screw could be used to anchor a cage into a
vertebral body through a small access site. A traditional straight
screw would require a large opening if a high angle screw
trajectory was desired. The flexible screw trajectory could be
curved, resulting in a much smaller opening for high angle screw
placement.
[0035] FIGS. 2A and 2B compare the trajectories of the screws
7.
[0036] Now referring to FIG. 3, once the cage is placed between the
vertebral bodies a curved stylet 9 is used to create the desired
high angle trajectory of the screw. The flexible screw 7 is then
placed over the stylet and a cannulated driver 11 engaged with the
external drive feature is used to rotate the flexible screw. Once
the screw 7 is fully seated the stylet can be removed, see FIG. 4.
The head of the screw keeps the cage from dislodging.
[0037] Therefore, in accordance with the present invention, there
is provided an intervertebral assembly comprising: [0038] a) an
intervertebral fusion device having an anterior wall, a posterior
wall, and first and second side walls connecting the anterior and
posterior walls, an upper bearing surface and a lower bearing
surface, the anterior wall having a height and an anterior surface,
and a first threaded throughhole extending into the anterior wall
from the anterior surface, [0039] b) a fixation device comprising a
proximal driving head and a distal flexible bellows having a
helical threadform disposed in the first throughhole, wherein the
helical threadform threadably mates with the first threaded
throughhole.
[0040] Preferably, the fixation device bellows has a throughhole
extending through the longitudinal axis thereof.
[0041] In general, and now referring to FIG. 5, the device is a
screw 7 that comprises three sections: a proximal head 13, an
intermediate flexible threaded hollow bellows section 15, and a
distal tip 17.
[0042] In some embodiments, and now referring to FIGS. 6A-B, the
head contains an internal drive feature 18 that mates with an
instrument to transfer torque to the screw causing it to advance
via the screw threads. The internal drive feature could be a hex,
hexlobe, or square. In some embodiments, there is also an axial
through-hole in the head to allow the screw to follow a guide wire.
The hole could be cylindrical or frustoconical: If the hole is
cylindrical 19, its diameter would need to be of sufficient size to
allow the screw head to pass over a curved guide wire. If the hole
is frustoconical 21, the narrow part of the frustocone would keep
the screw head centered but the wide part of the frustocone would
allow the head to pass over a curve in the guide wire.
[0043] Now referring to FIG. 7A, the screws used to fix the
stand-alone fusion cage in place must fasten to the cage to ensure
the cage does not migrate and the screws do not back out. One
method of securing the screws is to use a tapered threaded head 23.
Now referring to FIG. 7B, another embodiment uses a clip that mates
with a peripheral groove 25 in the head. Both of these means are
established locking mechanisms used in securing the bone screws to
plates and/or cages.
[0044] Now referring to FIG. 8, the bellows section 27 of the screw
is flexible and hollow, thereby allowing the screw to slide over
and follow the path of a guide wire. Helical threads formed by the
bellows enables the screw to axially advance when torque is
applied. The outer diameter of the threads should be less than the
diameter of the screw head, as this enables the screw threads to
pass through the hole in the cage or plate while the screw head
cannot.
[0045] Now referring to FIG. 9A-B, the distal tip of the device is
used to guide the screw along the guide wire and incorporates a
similar cylindrical 29 or frustoconical 31 axial through-hole as
the head. Also preferably incorporated on the tip are tapered
threads of the same pitch as the bellows threads. The threads of
the tip have an axial cut, thereby creating a flute as a cutting
edge.
[0046] Now referring to FIG. 10, the proximal head 33, intermediate
threaded bellows 35, and distal tip 37 can all be made separately
and joined together at first 39 and second 41 joints to create the
screw. Methods of joining could include welding, brazing, gluing,
or mechanical swaging.
[0047] The curved guide wire should be of a material that is stiff
and strong enough to maintain its curve while being inserted
through the cage or plate and into the vertebral body. Pre-curved
wires would be preferred to ensure the screw can flex appropriately
to conform to the guide wire.
[0048] Now referring to FIGS. 11A-B, a sleeve 43 can be used over
the guide wire 45 to create a slightly larger path in the vertebral
body. Once the sleeve is removed from the guide wire, the extra
space left by the sleeve will assist with screw insertion.
[0049] A centering guide 47 can be inserted into a hole 48 in a
plate or cage 49 to ensure the guide wire is located centrally in
the screw.
[0050] Spherical Hex Embodiment
[0051] In another embodiment, and now referring to FIGS. 12-14,
there is provided an inserter-device assembly wherein the driver
head of the fixation device incorporates a spherical hex. For the
purposes of the present invention, a "spherical hex" shape is a
spherical surface having six equally-spaced flats 51 around a
perimeter of the spherical surface 53. When a traditional ball and
socket joint is modified so that the spherical hex replaces the
ball and a hexagonal socket replaces the spherical socket, the
resultant design allows the transmission of torque between the two
components. The proximal end of the threaded "screw" component can
be either a male (head) or female (socket) end. A spring/ball
plunger or other means can be used to apply friction to the
spherical hex head to keep the two components rigidly engaged. Once
assembled, the mouth of the hex socket is deformed to close around
the base of the spherical hex head to ensure the two components do
not disassemble. The size and shape of the geometry of the neck at
the base of the spherical hex head helps determine how much
angulation is allowed. Although a hex has been described, any cross
section (square, pentagon, octagon, etc.) with flats to engage a
corresponding socket which allows the transmission of torque is
envisioned.
[0052] Therefore, in accordance with the present invention, there
is provided an intervertebral assembly comprising: [0053] a) an
intervertebral fusion device having an anterior wall, a posterior
wall, and first and second side walls connecting the anterior and
posterior walls, an upper bearing surface and a lower bearing
surface, the anterior wall having a height and an anterior surface,
and a first threaded throughhole extending into the anterior wall
from the anterior surface, [0054] b) a fixation device comprising a
proximal driving head and a distal shaft having a threadform
disposed in the first throughhole, wherein the threadform
threadably mates with the first threaded throughhole, and [0055] c)
an inserter having a distal endportion that mates with the driving
head, wherein the distal endportion of the inserter and the driving
head form a joint 55 comprising i) a head element 57 comprising a
spherical surface having a plurality of flats spaced equidistantly
along a perimeter of the spherical surface, and ii) a socket
element 59 comprising a mating surface mating with the plurality of
flats 61.
[0056] Preferably, the distal endportion of the inserter and the
driving head form a spherical hex joint.
[0057] Also in accordance with the present invention, there is
provided an intervertebral assembly comprising: [0058] a) an
intervertebral fusion device having an anterior wall, a posterior
wall, and first and second side walls connecting the anterior and
posterior walls, an upper bearing surface and a lower bearing
surface, the anterior wall having a height and an anterior surface,
and a first threaded throughhole extending into the anterior wall
from the anterior surface, [0059] b) a fixation device comprising a
driving head and a distal shaft having a longitudinal axis and a
threadform disposed in the first throughhole, wherein the driving
head comprises a spherical surface having a plurality of flats
spaced equidistantly along a perimeter of the spherical surface,
wherein the perimeter is substantially perpendicular to the
longitudinal axis of the shaft, and wherein the threadform
threadably mates with the first threaded throughhole.
[0060] In another embodiment, a cable is attached between the
distal screw end and a proximal socket. The ends of the cable can
be welded in place to rigidly attach the socket to the screw. The
cable provides flexibility yet allows the transmission of torque
between the socket and screw.
[0061] Slidable Gear Joint Embodiment
[0062] In another embodiment, and now referring to FIGS. 15-18,
there is i) a bone anchor 71 (or screw) having a shaft defining a
first longitudinal axis and helical threads 73 extending from the
shaft, and ii) a driver 75 also having a second longitudinal axis,
wherein the proximal endportion of the bone anchor slidingly
interfaces with the distal endportion of the driver in a manner
whereby the longitudinal axis of the driver and the longitudinal
axis of the screw are not necessarily collinear or parallel, but
rather form an oblique angle. The distal endportion of the driver
and the proximal endportion of the bone anchor each contains a
mating gear element 77, 79 so that rotation of the driver resulting
in driving the screw through the transmission of torque through the
gear. The driver and screw being positioned at an oblique angle
allows the driving to proceed without the requirement of in-line
force transmission. In some embodiments, the torque is transmitted
by a beveled gear mechanism having teeth on the screw and teeth on
the drive. Rotation of the driver about its longitudinal axis will
cause rotation of the screw about its longitudinal axis.
[0063] The mechanism for keeping the driver and screw engaged
(while the driver drives the screw) could take any of several
forms. The proximal endportion of the Screw can have a rotatable
post which extends proximally from the screw head along the screw
axis, wherein the post is retained by and rotatable along with the
body of the screw. The post preferably also has a transverse
opening 81 (such as a slot or a hole) to accept a distal portion of
the driver tip.
[0064] Therefore, in accordance with the present invention, there
is provided an intervertebral assembly comprising: [0065] a) an
intervertebral fusion device having an anterior wall, a posterior
wall, and first and second side walls connecting the anterior and
posterior walls, an upper bearing surface and a lower bearing
surface, the anterior wall having a height and an anterior surface,
and a first threaded throughhole extending into the anterior wall
from the anterior surface, [0066] b) a fixation device comprising
i) an elongate proximal projection defining a longitudinal axis and
having a throughhole extending transversely therethrough, ii) an
intermediate driving head having a first geared surface facing
proximally, and iii) a distal shaft having a threadform disposed in
the first throughhole, wherein the threadform threadably mates with
the first threaded throughhole, and [0067] c) an inserter having i)
an elongate distal endportion, ii) a proximal endportion having a
handle, and iii) an intermediate portion therebetween having a
second geared surface that mates with the first geared surface of
the proximal driving head,
[0068] wherein the elongate distal endportion of the inserter is
slidably received in the throughhole of the proximal projection of
the fixation device.
[0069] Preferably, the proximal projection of the fixation device
is detachable.
[0070] In a first preferred embodiment, the thoughhole of the
proximal projection of the fixation device defines: [0071] a) a
proximal inner surface disposed at an angle to the longitudinal
axis of the elongate proximal projection, wherein the angle us
between about 30 and 60 degrees, and [0072] b) a distal inner
surface disposed substantially perpendicularly to the longitudinal
axis of the elongate proximal projection,
[0073] In a second preferred embodiment the elongate distal
endportion of the inserter has a distal head thereon.
* * * * *